A tape-like magnetic recording medium has been conventionally prepared as follows: A ferromagnetic powder is blended with a binder, an organic solvent and other additives to form a magnetic coating composition in the form of a dispersion; then the composition is coated on a nonmagnetic support and dried thereon to form a wide-sized magnetic recording medium (web); and thereafter the web is slit into tapes each having a desired width, for example, 8 mm, 1/2 inch or one inch.
For purposes of slitting the web into tapes, a system such as shown in FIG. 2 is employed. Therein, a magnetic tape web (12) is slit into a plurality of tapes each having a desired width by means of slitter (21) which is composed of plural upper cutting blades (13), (14), (15) and (16) and lower cutting blades (17), (18), (19) and (20), and the thus slit magnetic tapes (22) and (24) are reeled up to a pancake (27) via a guide roller (26). Another pancake for reeling up other magnetic tapes (23) and (25), which is comparable to pancake (27), is not shown in FIG. 2.
In the practice of slitting the web into the plurality of tapes by the system above, it has been suggested that it is preferable to smooth the cross sectional profile of the edge portion of the magnetic tape as slit, or to give the edge profile a rounded configuration, in order that the tape is not as readily soiled, or the tape head is not as easily soiled when the tape is set in a cassette and run over the head in a cassette player. Moreover, almost conventional tapes, in actual practice, were slitted to have such smoothed or rounded shapes.
For instance, for purposes of smoothing the cross sectional profile of the edge of a magnetic tape, a method has been employed wherein the unslit tape or web has a Young's modulus (M.sub.0.5) of 550 kg/mm.sup.2 or more and the unslit tape or web is slit at a high slitting speed of approximately 300 m/min.
On the other hand, for purposes of making a round cross sectional profile in the edge portion of a magnetic tape, a method has proposed of using a laser beam for slitting the tape (JP-A-64-78426 and JP-A-64-78427 (the term "JP-A" as used herein refers to a "published unexamined Japanese patent application").
However, the tape, as slit by the above mentioned conventional methods, has a drawback in that the rolled-up form of the tape is not completely aligned at the tape edge when the tape is wound up by FF/REW mode. Although the tape is not soiled itself and it does not soil the head during general recording and reproduction mode, the aforementioned drawback has arisen with use of this type of tape which was given a smoothed or rounded edge.
This problem is illustrated in FIG. 3. In particular, a magnetic tape (32) is wound up into a reel (28) in a cassette arranged horizontally. As depicted in FIG. 3, the rolled tape has a projected part (33) due to non-alignment in sequentially wound layers of the tape. This non-alignment at the tape edge undesirably affects the rolled-up form of the tape in the above mentioned FF/REW mode. The magnetic tape, which had been wound-up to have such a non-aligned rolled-up form, would cause fluctuation of the condition of the tape when run over the magnetic head. As a result, the image being reproduced from the tape would unfavorably be rendered uneven. In FIG. 3, element (29) is an upper flange, element (30) is a lower flange and element (31) is a reel shaft.